Evaluation of renal masses with contrast-enhanced rapid acquisition spin echo MR imaging.

To assess the use of dynamic contrast-enhanced rapid acquisition spin-echo (RASE) imaging for the detection and characterization of renal masses, we evaluated 18 patients with CT evidence of 67 renal masses. The masses included 58 simple cysts, 8 solid neoplasms, and 1 pseudotumor. Patients were examined with standard spin-echo (SE) pulse sequences including pre- and postcontrast T1-weighted images and noncontrast T2-weighted images as well as pre- and postcontrast RASE images. Each pulse sequence was reviewed individually and in a group with other pulse sequences by two blinded observers. The performance of contrast-enhanced RASE imaging either alone or in combination with a T2-weighted SE sequence resulted in improved diagnostic accuracy compared with unenhanced conventional SE and RASE sequences. The contrast-enhanced RASE sequence outperformed the contrast-enhanced T1-weighted SE sequence for one observer; similar diagnostic accuracy was achieved with the two examinations by the other observer. Combining the T2-weighted sequence with contrast-enhanced RASE images did not increase lesion detection but did increase the observers' confidence in making the diagnosis. Contrast-enhanced MR imaging resulted in significant improvement in the detection and characterization of renal lesions compared to unenhanced MR imaging.